Photochemical degradation of iodate by UV/H 2 O 2 process: Kinetics, parameters and enhanced formation of iodo-trihalomethanes during chloramination

• Published in: Chemosphere (Oxford) Vol. 221; p. 292
• Main Authors: Tian, Fu-Xiang, Ma, Shi-Xu, Xu, Bin, Hu, Xiao-Jun, Xing, Hai-Bo, Liu, Jing, Wang, Juan, Li, Yuan-Yi, Wang, Bo, Jiang, Xia
• Format: Journal Article
• Language: English
• Published: England 08.01.2019
• Subjects: UV/HO; Iodo-trihalomethanes (I-THMs); iodate (IO(−)); Chloramination
• ISSN: 1879-1298

In this paper, it was demonstrated that UV/H O process can not only obviously promote the degradation rate of IO , but also greatly enhance iodo-trihalomethanes (I-THMs) formation in sequential chloramination. UV/H O exhibited much faster IO decomposition than either UV or H O treatment alone due to the contribution of highly reactive species including O , OH and e . The degradation rate of IO was affected by H O dosages, pH, UV intensity as well as the presence of natural organic matter (NOM). The calculated pseudo-first order rate constant gradually increased with H O dosages and solution pH, but behaved directly proportional to the UV intensity. Although NOM remarkably reduced the degradation rate of IO in UV/H O process, their presence greatly enhanced the formation of I-THMs during subsequent chloramination. The overwhelming majority of iodoform at high UV fluences was also observed, which indicated improved iodination degrees of the detected I-THMs. UV/H O was proved to be more capable on the evolution of IO to I as well as I-THMs than UV and thereby enhanced the toxicity of disinfected waters in the following chloramination process. This study was among the first to provide a comprehensive understanding on the transformation of IO as the emerging iodine precursor to form I-THMs via diverse advanced oxidation process technologies like UV/H O .